Centrifugal drier

ABSTRACT

A centrifugal drier comprises a tubular rubber sleeve mounted in the path of the trajectory of solid particles centrifugally ejected from a drying basket into a casing surrounding the basket. The axes of the drying basket and the rubber sleeve are parallel and one end of the sleeve is rigidly affixed to the casing. A weight is carried by the other sleeve end to which a reciprocating motion is imparted substantially parallel to the axes whereby the elastic rubber sleeve is alternately elongated and contracted.

United States Patent Mercier Get. 29, 1974 CENTRIFUGAL DRIER 3,366,245 1/1968 Mercier 210/378 Inventor: Andre Mercier La Madeleine 3,724,091 4/1973 Rousselet 34/58 France Primary ExaminerCharles N. Hart [73] Assignee: Fives Lille Call, Paris, France Assistant 1= F l i [22] Filed; May 21, 1973 Attorney, Agent, or Firm-Kurt Kelman [21] Appl. No.: 362,320

[57] ABSTRACT [30] Foreign Application Priority Data A centrifugal drier comprises a tubular rubber sleeve Ma 1 9 I 972 Fm C6 72 018006 mounted in the path of the trajectory of solid particles y n centrifugally ejected from a drying basket into a casing surrounding the basket. The axes of the drying C 210/378 4 basket and the rubber sleeve are parallel and one end [58] Fie'ld 34/9 of the sleeve is rigidly affixed to the casing. A weight 68/19 is carried by the other sleeve end to which a reciprocating motion is imparted substantially parallel to the [56] References Cited axes whereby the elastic rubber sleeve is alternately elongated and contracted.

8 Claims, 1 Drawing Figure CENTRIFUGAL DRIER The present invention relates to improvements in centrifugal driers for the continuous drying of liquidsolid mixtures, such as sugar juice. It is more particularly concerned with driers of this type wherein solid particles are centrifugally ejected at high speed against an elastic wall or baffle mounted in the path of the trajectory of the ejected particles in a casing surrounding the drying basket whereby the impact of the particles is cushioned and the particles are deflected into a particle collecting receiver.

To avoid breakage of the particles at the baffle wall, it has been proposed to make the wall in the form of a sleeve of elastic material, such as rubber. which absorbs the impact energy of the particles without breaking them.

A centrifugal drier of such a type. has been disclosed, for instance, in my copending application Ser. No. 356199 filed May l, 1973, under the the title Continuous Drying of Solid Particles." As far as pertinent hereto and to supplement the disclosure of the drier structure herein, the entire disclosure of my copending application is incorporated in this application, thus avoiding redundancy.

It has been found that an elastic baffle and deflecting wall of the type therein disclosed is rapidly made ineffectual by deposits formed thereon when the particles are still moist and sticky.

It is the primary object of this invention to avoid this difficulty, which is accomplished by alternatively elongating and contracting the elastic sleeve so as to prevent any particle deposit to be formed thereon.

The above and other objects are obtained in accordance with the invention with means for rigidly affixing one of the elastic sleeve ends to the casing, a rigid body carried by the other sleeve end, and means for imparting to the rigid body a reciprocating motion substantially parallel to the axes of the rotary drying basket and the casing surrounding the basket whereby the elastic sleeve is alternately elongatedand contracted.

The elastic sleeve, which is mounted in the path of the trajectory of the ejected particles in the casing to receive the ejected particles, may be cylindrical or frustoconical, the axis of the sleeve being substantially parallel to the axis of the drying basket.

in case the axes are vertical. the upper end of the sleeve is rigidly affixed to the casing while a weighted rigid body is carried by the lower end of the sleeve so that the weighted body oscillates vertically when it is removed from its position of rest. Periodic downward pulses are imparted to the body to keep the oscillations going. The frequency of the oscillations will depend on the mass of the weighted body and the rigidity of the elastic material forming the sleeve. This frequency being selected to obtain the desired reciprocation. This frequency may be modified. if desired, by resiliently biasing the rigid body downwardly, for instance by a compression spring mounted between the casing and the body.

According to one feature of the invention, the reciprocating motion imparting means may include electromagnets mounted on the casing'and having movable armatures connected to the rigid body by rods.

According to another feature of this invention, the rigid body may be a ring comprising a frusto-conical element disposed adjacent the frusto-conical sleeve at a small distance therefrom to limit the deformation of the elastic sleeve.

In accordance with a preferred embodiment of the present invention, the elastic sleeve is frusto-conical, the small base of the frusto-conical sleeve being affixed to the casing and the large base thereof being affixed to the annular rigid body, the angle of inclination of the frusto-conical element extending upwardly from the annular rigid body in respect of the sleeve axis being slightly inferior to the angle of the sleeve to the axis thereof whereby, in the equilibrium position of the rigid body. a gradually increasing space is defined between the element and the sleeve from the large to the small base thereof.

The above and other objects, advantages and features of the invention will become more apparent from the following detailed description of a preferred embodiment thereof, taken in conjunction with the single FIGURE ofthe accompanying drawing which shows a vertical section of the upper portion of one half of a centrifugal drier incorporating the features of this invention, the other half (notshown) being symmetrical to the illustrated half of the drier.

Referring now to the drawing, which is merely illustrative of the present invention by way of example and whose conventional parts are shown merely schematically, the drier comprises rotary drying bowl or basket I mounted for rotation about vertical rotary axis 18. In a conventional manner, the liquid-solid mixture to be dried is supplied to basket 1 along the axis 18 thereof. During rotation of the basket at high speed, the liquid phase of the mixture is separated or filtered through screen or sieve la mounted along the wall of the basket, the liquid being removed through ports in the basket wall leading into annular chamber 20 surrounding the basket.

Also as conventional, the solid particles separated on screen In from the liquid phase glide upwardly along the screen during rotation of the basket and are centrifugally ejected at the upper endof the basket along trajectory 19 into a drying chamber defined by casing 22 closed by casing cover 21.

As also described in my above-mentioned prior patent application, a sleeve 2 of an elastic sheet material, such as rubber, is mounted in the path of the trajectory 19 of the ejected particles along the periphery of the drying chamber in casing 22, the drying basket and the frusto-conical sleeve being coaxial. The elastic sleeve 2 cushions the impact of the particles and deflects them so that they fall by gravity into the bottom of the casing 22 wherefrom they are removed in any desired manner,

in the illustrated embodiment, each end of the elastic sleeve 2 had a flange or bead which may be reinforced by textile fibers or steel filaments. The upper end or small base of the frusto-conical sleeve is rigidly affixed to the casing by means of a circular support 3 which is mounted on, or integral with, casing cover 21. The support defines an annular groove receiving the upper bead of 'thesleeve, a clamp or strap 4 extending over the bead and holding the bead in the groove. Screws or like fastening elements attached the clamp 4 to support 3 to clamp the upper end of the sleeve to the support.

An annular weighted rigid body 6 is carried by the lower end of sleeve 2. This lower end also has a reinforced bead received in a groove in the rigid body, this bead being clamped to the body by strap or clamp 7 fixed to the body by screws 8.

The weight of rigid body 6 causes the elastic sleeve 2 to'be elongated or stretched. If desired, this elongation may be increased by mounting a compression spring 9 between the annular body 6 and easing cover 21 so as to bias the weighted body downwardly.

This assembly constitutes an oscillating means. If the ring 6 is moved from its position of rest or equilibrium, it begins to oscillate vertically with a frequency which depends on the mass of the ring and the elastic characteristics of sleeve 2 and spring 9. This oscillation or reciprocatory motion may be maintained by imparting to ring 6 pulses in phase with this motion.

Generally, it will be desirable to hold the oscillation down to a low frequency and an appreciable elongation of the sleeve to produce the desired effect of removing any deposits sticking to the sleeve wall.

In the illustrated embodiment, these pulses are imparted to ring 6 by rods 10. Since the-pulses are feeble, the assembly oscillating at its own frequency, it will be sufficient to use two rods 10 engaging ring 6 at diametrically opposed points. Synchronized pulsators are connected to the upper parts of the rods.

As shown, these pulsators may be electromagnets 11 mounted on bridges or brackets 12 fixed to casing cover 21. When the electromagnets are energized, their armatures 13 will engage their cores and move them downwardly to compress spiral spring 14 mounted between the core and a collar fixed to the upper part of rod 10. This will impell the rod downwardly.

The periodic energization of electromagnets 11 is controlled by a system which permits regulation of the frequency and duration of the pulses.

Obviously, the electromagnetic pulsators may be replaced by a mechanical, hydraulic or pneumatic system for impelling the annular body 6.

The annular rigid body 6 is shown to have a frustoconical element or crown 16 whose large base is integral with the body and which surrounds the elastic sleeve 2. The angle of inclination of element 16 is slightly inferior to that of the sleeve so that, when the body 6 is at rest, the space between the element 16 and the sleeve 2 gradually increases from the large base to the small base of the element 16 so that the elastic sleeve will progressively engage the element as it is stretched by the downwardly displacement of ring 6. In this manner, undue deformation of the sleeve is avoided in case a massive body is ejected from the drying basket and hits sleeve 2.

A thin and deformable rubber membrane 17 is fixed to the casing and to ring 6, respectively, this annular membrane closing off the space between sleeve 2 and casing 22 in the upper portion thereof from the drying chamber within the casing between the drying basket and the casing wall, whereinto the solid particles fall 2. means for rigidly affixing one of the sleeve ends to the casing, 3. a rigid body carried by the other sleeve end, and

4. means for imparting to the rigid body a reciprocating motion substantially parallel to the axes whereby the elastic sleeve is alternately elongated and contracted.

2. In the centrifugal drier of claim 1, the axes being substantially vertical, and the rigid body constituting a weight.

3. In the centrifugal drier of claim 2, spring means biasing the rigid body downwardly.

4. In the centrifugal drier of claim 2, the reciprocating motion imparting means including electromagnetic means.

5. In the centrifugal drier of claim 2, the tubular sleeve being frusto-conical.

6. In the centrifugal drier of claim 5, the rigid body comprising a frusto-conical element disposed adjacent the sleeve, theangle of the frusto-conical element in respect of the sleeve. axis being slightly inferior to the angle of the sleeve to the axis thereof whereby, in the equilibrium position of the rigid body, a gradually increasing space is defined between the element and sleeve.

7. In the centrifugal drier of claim 1, beads on the sleeve ends, and means for clamping the beads to the casing and the rigid body, respectively.

8. In the centrifugal drier of claim 1, an annular deformable membrane attached, respectively to the casing and to the rigid body whereby the space defined between the sleeve and the casing is closed off from the space between the basket and the sleeve. 

1. In a centrifugal drier for the continuous production of dried solid particles, which comprises a rotary drying basket having an axis, and a casing surrounding the basket and receiving the solid particles centrifugally ejected from the basket in a trajectory:
 1. a tubular sleeve of an elastic material mounted in the path of the trajectory in the casing to receive the ejected particles, (a) the sleeve having two ends and (b) an axis substantially parallel to the basket axis,
 2. means for rigidly affixing one of the sleeve ends to the casing,
 3. a rigid body carried by the other sleeve end, and
 4. means for imparting to the rigid body a reciprocating motion substantially parallel to the axes whereby the elastic sleeve is alternately elongated and contracted.
 2. means for rigidly affixing one of the sleeve ends to the casing,
 2. In the centrifugal drier of claim 1, the axes being substantially vertical, and the rigid body constituting a weight.
 3. In the centrifugal drier of claim 2, spring means biasing the rigid body downwardly.
 3. a rigid body carried by the other sleeve end, and
 4. means for imparting to the rigid body a reciprocating motion substantially parallel to the axes whereby the elastic sleeve is alternately elongated and contracted.
 4. In the centrifugal drier of claim 2, the reciprocating motion imparting means including electromagnetic means.
 5. In the centrifugal drier of claim 2, the tubular sleeve being frusto-conical.
 6. In the centrifugal drier Of claim 5, the rigid body comprising a frusto-conical element disposed adjacent the sleeve, the angle of the frusto-conical element in respect of the sleeve axis being slightly inferior to the angle of the sleeve to the axis thereof whereby, in the equilibrium position of the rigid body, a gradually increasing space is defined between the element and sleeve.
 7. In the centrifugal drier of claim 1, beads on the sleeve ends, and means for clamping the beads to the casing and the rigid body, respectively.
 8. In the centrifugal drier of claim 1, an annular deformable membrane attached, respectively to the casing and to the rigid body whereby the space defined between the sleeve and the casing is closed off from the space between the basket and the sleeve. 